PARASITIC WEAVERBIRDS 115 



December 12: Third day: Two weak chicks are being fed. There 

 are still two unhatched eggs. 



December 13 : Fourth day: Another egg has hatched (the remaining 

 egg does not hatch and a few days later is found outside the nest). 

 The newly hatched chick looks absurdly small beside the others, 

 but it is quite vigorous. No seeds are visible in its throat. The 

 quills of the primaries show in larger birds. Pintail: Quills are 

 emerging on prunaries and secondaries. 



December 14: Fifth day: Pintail: Quills are out on primary and 

 secondary coverts. Its eyes are half open. 



December 16: Seventh day: Pintail: Quills are emerging on the 

 back, rump, tail, breast, flanks, and humerals. 



December 17: Eighth day: Estrilda: Quills are out on the back, 

 rump, tail, humerals, breast, and flanks. The eyes are half open. 

 Pintail: Crown and throat quills are out. Natal down still adheres. 



December 18: Ninth day: Estrilda: Quills are out on crown, but 

 not on throat or chin. The eyes are half open. Pintail: Chin 

 quills, frons, superciliaries, and ear coverts are out. Feathers are 

 breaking thi'ough on primaries and their coverts, and on secondaries 

 and their coverts. The eyes are open and bright. 



December 19: Tenth day: Estrilda: Quills are out on chin, super- 

 ciliaries, and ear coverts. Remiges are breaking out of the c[uills. 

 Pintail: AH feathers are emerging, except on the head. 



December 20: Eleventh day: Pintail: Feathers on the head are 

 all out. Body skin is not yet covered by feathers. The squeak of 

 the parasite is unlike that of the young waxbiUs. 



December 22: Thii-teenth day: Pintail: Obviously is different from 

 young waxbills. Cannot now handle it for fear of disturbing. 



December 30: Twenty-fii'st day: All have left nest. 



Summary: The durations of the nestling periods were as follows: 

 One pintail and 1 Estrilda about 20 days ; 2 Estrildas about 19 days. 

 One Estrilda died. There was a difference in the vocalisms of the 

 young waxbill and the pintail when both were ready to leave the nest. 

 The waxbill gave a chewnk call much like the adult, while the pintail 

 gave a husky, plaintive wehk-wehk-wehk call, to which the foster 

 parents responded. The pintail also uttered a harsh, husky screech 

 when picked up and handled. As with the foster parents of all para- 

 sitic birds, these foster parents showed no apparent discrimination 

 between their own chicks and those of the parasite. Here, unlike 

 some of the other cases, there is not so great a difference in size and 

 appearance between them. 



Chapin (in litt.) found a nest of the common waxbill in the Lwiro region, 

 eastern Belgian Congo that contained a nestling pintail and some 

 young nestlings of the host. He was able to compare the amazingly 



